Radio Habana Cuba
Dxers Unlimited
Dxers Unlimited's mid week for 18-19 October 2005
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados... welcome to the mid week edition of Dxers
Unlimited, coming to you from Havana... I am back home after a flash one
week trip to attend a UNESCO meeting in Paramaribo, Suriname, where I was
able to set aside a little time for monitoring the bands.... So today, we
will be able to provide our popular HF plus low band VHF propagation update
and forecast... I am Arnie Coro, radio amateur CO2KK, and as always it's my
pleasure to share with you about seventeen minutes of air time... Item one:
As I was starting to write the script of this program, at around 10 hours
UTC, that is six o'clock in the morning local time here in Havana, Cuban
broadcast stations were providing extensive coverage to developing tropical
storm WILMA, that according to forecasters will develop into al dangerous
hurricane in the next few hours... The Cuban weather service top hurricane
expert, my good friend
Doctor Jose Rubiera Ph.D. presented a special report to Cuban television
Monday evening, in which he offered a very detailed and comprehensive
analysis of how tropical storm WILMA was most likely to develop during the
next several days, and he warned people living in western Cuba, the Cayman
Islands, areas of Central America between Honduras and Nicaragua as well as
southeast Mexico especially the Yucatan peninsula... This weather related
event has already mobilized a large number of Cuban amateur radio operators,
who at this moment that you listen to Dxers Unlimited are already providing
emergency communications to areas of eastern Cuba where the heavy rains
associated with tropical storm WILMA have already left several communities
isolated by land, due to several rivers overflowing their banks and
producing floods. Guantanamo and Santiago de Cuba radio amateurs are
operating emergency nets on the two meters band, using several repeaters
located at mountaintops that provide excellent coverage... More about
amateur radio and hurricanes later in today's edition of Dxers Unlimited....
Now item two: Several well known scientists in the area of solar research
are now carefully reviewing the most recent solar data, because they may
give the clue to tell us if solar cycle number 23 had already passed trough
its minimum.... According to some scientists , the minimum was expected to
happen sometime between the end of 2006 and the first few months of 2007..
But, the current montly averages of solar activity shows that it is rising
again after a period of very low activity .
Item three: A low antenna height is essential for obtaining the high angle
radiation required for close range communications during emergencies... More
about antennas for hurricane emergencies later in this mid week edition of
Dxers Unlimited, that will continue in just a few seconds , after a brief
musical interval... I am Arnie Coro in Havana...
.....
Solar minimum already .... is solar cycle 24 already in progress ? I will be
asking today our Cuban solar expert Angel Gonzalez Coroas about this topic,
and bring his analysis to you during the upcoming weekend edition of the
program. Now more about radio amateurs and emergency communications ... 40
meters band antennas that are going to be used for handling emergency
traffic , must be installed close to the ground, at a height of no more than
5 to 6 meters at maximum... A half wave dipole cut for the 40 meters band ,
placed between two masts of between 5 and 6 meters, will produce an optimum
vertical radiation pattern that will provide short range coverage with high
intensity signals , exactly what is required to handle emergency
communications in the immediate vecinity, without the need to use repeaters
A similar antenna system for the 80 meters band placed at a 90 degrees
angle and fed with the same coaxial cable will provide your emergency
station with excellent night time short range coverage... This type of
installation may be accomplished using a centrally located 6 meters high
mast, and four smaller ones of about 4 meters length.
HF, that is short wave signals bouncing from the ionosphere back to Earth
don't require line of sight paths, and reach places where 2 meters and 70
centimeters repeater stations don't provide coverage. A typical 100 Watt HF
transceiver, operating at half power to save battery power feeding this
cross 40 and 80 meters antenna will provide strong signals in an area of
around 300 to 500 kilometers around the station, whenever the Near Vertical
Incidence Radition mode is present.
After I finish recording today's program, I will resume preparations
required to face what may well be yet another intense tropical hurricane
passing near or over western Cuba...
.....
SI amigos, this is the mid week edition of Dxers Unlimited, coming to you
from Havana... and here is one more radio hobby related item that was
requested by several listeners that wrote e-mail messages to arnie@rhc.cu...
they all wanted to learn more about the different types of so called
survival or emergency radios, as there seems to be a lot of discussions
going on about which type of generator is best for that application. Well
amigos, there are essentially three sources of alternative energy to
recharge nickel cadmium , nickel metal hydride or the more recent lithium
ion batteries... The Bayliss clockwork generator, the hand cranked direct
current generator and solar photovoltaic cells... One can also use the so
called primary alkaline cells, that are not very popular because they are
difficult to handle and weight a lot... O f the three sources of electricity
for the emergency radios, one is out of the question during bad weather
conditions, but will work very nicely once the hurricane has passed, leaving
the unusually blue clear sky with intense solar radiation . So for the
duration of the storm, the Bayliss clockwork, and the handcrank charger are
the two options available. My favorite is the direct crank up DC generator
because it is much more rugged and reliable than the Bayliss clockwork
generator. Hand cranking the generator for periods as short as a few minutes
or a long as a half hour can produce enough electricity to charge a typical
6 volts battery pack so that you can operate your radio receiver for several
hours...thus allowing you to keep well informed about the proximity of the
hurricane, and be able to follow instructions given by the local authorities
handling the emergency. So amigos, after several hurricanes here, I pass
along this information to you... stay away from the clockwork Bayliss
generator and look for emergency radio receivers that do not use wind up
clockwork systems... look for crankup DC generators , as they are much more
reliable and work well even if your batteries are in very poor shape...
According to the most recent Cuban weather service forecast, hurricane WILMA
should be reaching western Cuba , the straight of Yucatan, or southeastern
Mexico by Friday, the final track depending on the interaction of the storm
with the two anticyclones high pressure areas located to the east and west
of Wilma...And by the way, the 5 day forecast shows that South Florida may
also be hit by hurricane Wilma if the path shifts more to the north , north
east.
.......
Si amigos, ASK Arnie is definetely the most popular section of Dxers
Unlimited... your radio hobby related questions continue to come in to
arnie@rhc.cu, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba
.. Here is now today's question... coming from listeners in the USA, Canada,
Malaysia,Germany and Norway...They all want to know more about the HF
propagation forecast for the month of November... The reason for their
question is related to a recent comment made here a few weeks ago, in which
I explained that the month of November will produce the best HF propagation
conditions for those of us leaving in the Northern Hemisphere... Well amigos
this is going to be the last really good month of HF propagation for almost
a year... IF, and I repeat IF, solar cycle 23 is still to reach a minimum by
the end of 2006 and the begining of 2007... If on the contrary, as we said
at the start of today's program , solar cycle 23 has already reached minimum
, then things will be a bit different , because we should expect another
four to eight week period of good propagation during the 2006 spring
equinoctial season.. With solar flux figures expected to reach no more than
100 units at the monthly peak next November, my propagation analysis show
that some paths will be able to provide even 10 meters band openings, and
that the 15 meters amateur band will be the best one for Dxing during the
local daytime hours...But again, try to call CQ DX on 10 meters as many
times as possible, as that band is going to see more openings during
November tahn during the past six months... The early winter Dx season of
2005 will be an excellent opportunity to work many new DX entitities to add
to your DXCC record !!!
......
And now as always when I am here in Havana, this is Arnie Coro's Dxers
Unlimited HF plus low band VHF propagation update and forecast... The
sunspot number is pretty low , just eleven, a typical figure of solar
minimum periods... Solar activity will be very low, and there are no
sunspots on the farside of the Sun... Expect solar flux figures around 85
units, and a rather quiet geomagnetic field. Best bands for daytime Dxing
are in the range from 15 to 20 megaHertz, and for the local evening hours,
your best time frame for Dxing will be from just after sunset to just before
sunrise, and the band of frequencies that will provide optimum results are
between 4 and 12 megaHertz...
See you all at the weekend edition of Dxers Unlimited, next Saturday and
Sunday
UTC... Don't forget to send me your signal reports, comments about the
program and radio hobby related questions to arnie@rhc.cu, or VIA AIR MAIL